Where’s the Daddy Wage Gap?

Statistics show that with each child they have, women lose ground on wages when compared to non-mothers.
It’s been dubbed the “Mommy Wage Gap”:
For the first child a woman has, the wage differential in comparison to nonmothers is from 2 to 10 percent less.
For the second child, the gap is from 4 to 16 percent less than for women with no children.
It’s not surprising that the primary caretaker’s wages suffer as the family grows. But I can’t stand the fact that this conversation never revolves around mothers’ and fathers’ respective levels of involvement in parenting.
Indeed, polling shows “American workers are divided as to which parent has to work harder to achieve work/life balance.”
Oh, come on. If that’s really true, then why isn’t there a Daddy Wage Gap?